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Re: [TowerTalk] ICE 419B schematic

To: towertalk@contesting.com
Subject: Re: [TowerTalk] ICE 419B schematic
From: Mark Ketchell <k5er@arrl.net>
Date: Tue, 19 Jul 2011 16:48:17 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Okay, I'll ask too...

The 20 meter section of my ICE 419b failed - infinite SWR.

I removed cover from relay and polished contacts, eliminating it as the 
possible failure point.

Inductors - still same size and shape, can't be them.

Pulled the 3 caps and took to elec supply store. All 3 checked good on 
their tester (had them check twice). Took to friend with HP meter. The two 
shunt caps (.001 @ 2kv) each checked fine - the 270 pf (+/- 5%) checked as 
251 pf - about 7% off. Would have thought it was close enough to find a 
resonate point, but it would not.

I simply replaced all three and it works just like new.

Why would the caps check as okay, but be absolutely worthless in the 
circuit?  IF it is the series cap (270pf at 1kv) that fails, then why 
doesn't it ever seem to take the .05 @ 200v series cap right at the antenna 
port? If not the series cap, how does a 100 watt radio generate enough 
voltage to cause a 2kv cap to fail? There are resonate auto-switched 
antenna on each band, so it "shouldn't" see high SWR.

Thanks,
Mark


...
>What usually happens when the filter fails is that one or both of
>the capacitors on the radio side of the Pi changes value.
>
>Mouser has a good selection of heavier-duty replacement caps.
>For example, Mouser part number 5983-19-1KV330 for 15 meters.
>Even with those, the filter can still fail.
>
>Dave Hachadorian, K6LL
>Big Bear Lake, CA
>
>
>-----Original Message-----
>From: James C. Hall, MD
>Sent: Monday, July 18, 2011 2:28 PM
>To: towertalk@contesting.com
>Cc: tcg1@googlegroups.com
>Subject: [TowerTalk] ICE 419B schematic
>
>Hello:
>
>I sent an email to ICE inquiring about their ability to repair my
>ICE 419B's
>which have a couple blown filters. I got a response that since
>Mike died,
>they can't repair anything right now.
>
>I asked about a schematic of these 2-stage filters and they came
>back with
>'they don't have them either', which I found rather strange. At
>any rate,
>does anyone have a schematic or parts list of the 419B so that I
>may attempt
>to fix them myself ?
>
>This may or may not be the correct forum to send this, so if not,
>please
>advise and I'll redirect this.
>
>Thanks.
>
>73, Jamie
>
>WB4YDL

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